Abstract P6-05-01: Triple Negative Breast Cancer in Korea — Distinct Biology with Different Impact of Prognostic Factors on Survival

Background: Patients with triple negative breast cancer(TNBC) are known to have poor prognosis and derive no benefit from endocrine therapy or targeted treatments. Using a database from a multicenter registry in Korea, we present the clinical features and prognosis for TNBC with other subtypes of breast cancer and clinicopathologic variables that influence the 3-year survival of the TNBC patients.

Materials and Methods: From 1993 to 2008, patients diagnosed with breast cancer who were registered to the Korean Breast Cancer Society Registry were analyzed retrospectively. A cohort of 26,767 patients were divided in four groups: luminal A (ER+ and/or PR+, HER2-), luminal B (ER+ and/or PR+, HER2+), HER2 overexpression (ER-, PR-, HER2+), and triple negative (ER-, PR-, HER2-). Clinicopathologic features such as age, tumor size, nodal status, p53, ki-67 expression and survival were evaluated. Results: The luminal A (14437 patients, 53.9%) subtype was the largest in our study sample, as compared with luminal B (3517 patients, 13.1%), ER-/HER2+ (3227 patients, 12%), and TNBC (5586 patients, 21%) subtypes. Compared with luminal A subtype, TNBC correlated with younger age and more aggressive characteristics, such as larger size, more lymph node metastasis, and higher proliferation rate. Moreover, TNBC correlated with poor overall survival and breast cancer-specific survival. The hazard rate showed a peak at 24 months for the TNBC subtype, but after 60 months, the risk was similar to that of the luminal A subtype. Higher T, N stage and histologic grade, and lymphatic and vascular invasion showed poor prognosis in TNBC patients, but on multivariate analysis only histologic grade and ki-67 status were related to poor prognosis. Young age was related to poor prognosis in the luminal A subtype, however, age was not related to prognosis in the TNBC subtype. Of the 5586 TNBC patients, 282 patients (7.11%) expired within 3 years of diagnosis. T and N stage, and grade was significantly associated with prognosis on multivariate analysis.

Discussion: TNBC subtype is characterized by a younger age with poorer outcome. However, younger age is not related to prognosis, and mortality risk decreases to that of the luminal A subtype, which is known to have the best prognosis after a few years. The underlying biology of the TNBC subtype is important, and further studies to discover novel biomarkers to predict prognosis and target treatments for the TNBC subtype are necessary.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-05-01.

Multimodal optical and Gd-based nanoparticles for imaging in inflammatory arthritis

OBJECTIVES

This report documents a multimodal nanoparticle (MNP) contrast agent, containing embedded luminophores and surface-immobilized gadolinium chelates, as a contrast agent of inflamed synovium in a collagen induced arthritis (CIA) model.

METHODS

DBA-1J mice were immunized for CIA and imaged after disease onset by two independent modalities. After intravenous administration of MNP contrast, optical and magnetic resonance images were obtained and clinical disease was scored, which was followed by processing of hindlimbs for immunofluorescence and confocal microscopy.

RESULTS

We show a correlation between disease severity and MNP optical luminescence that is dose dependent. Immunofluorescence of hindlimb sections reveal that MNP-labeled cells are monocytes/macrophages within the inflamed synovium. Magnetic resonance (MR) relaxation time maps, which determine the quantitative measure of T1 and T2 values at each imaging voxel, demonstrated a decreasing T2 signal in actively inflamed joints that was more pronounced earlier rather than later during disease.

CONCLUSIONS

MNPs containing surface-immobilized gadolinium chelates and embedded luminophores are potential dual-modality contrast agents in inflammatory arthritis and localize to monocytes/macrophages within inflamed synovium.

Serum glycan analysis in metastatic breast cancer

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Background: There is a need for a reliable breast cancer biomarker that can predict a patient’s response to therapy. Serum glycans, or oligosaccharides, are of particular interest as over half of all proteins are glycosylated and alterations in glycosylation influence growth, adhesion, metastasis and immune surveillance of tumor, among other important functions. Serum glycans can be analyzed by high resolution mass spectrometry. Methods: Sera from patients with known metastatic breast cancer and age-matched healthy controls without medical problems were prospectively analyzed by mass spectroscopy. Women over the age of 18, who were not pregnant or breastfeeding, and who were without other active cancers were eligible. Samples were de-identified for laboratory personnel who analyzed sera by matrix-assisted laser desoprtion/ionization (MALDI) and Fourier transform ion-cyclotron resonance mass sepctrometry (FT ICR MS). Glycans were also profiled by chromatographic separation using a microchip nanoLC (Agilent) with a time-of-flight (TOF) mass analyzers. Results: Sera from 25 patients with metastatic breast cancer and 25 controls were evaluated. The mass profiles were obtained corresponding to both N-linked oligosaccharides (N-glycans) and O-linked oligosaccharides (O-glycans). Distinct variations in glycosylation were observed among sera analyzed from patients with metastatic breast cancer compared to controls. Specific glycan masses were analyzed and found to correspond to N-glycans. The chromatographic glycan profile showed individual glycans that were distinct for the cancer patients. Conclusions: Analysis of serum gylcans by mass spectrometry represents a new paradigm of cancer biomarker studies, focusing on post-translational modifications of proteins, rather than protein expression. Further refinement of this technology may be clinically useful in monitoring response to therapy in metastatic breast cancer.

No significant financial relationships to disclose.

Aberrant methylation of the Wnt antagonist SFRP1 in breast cancer is associated with unfavourable prognosis

The canonical Wnt signalling pathway plays a key role during embryogenesis and defects in this pathway have been implicated in the pathogenesis of various types of tumours, including breast cancer. The gene for secreted frizzled-related protein 1 (SFRP1) encodes a soluble Wnt antagonist and is located in a chromosomal region (8p22-p12) that is often deleted in breast cancer. In colon, lung, bladder and ovarian cancer SFRP1 expression is frequently inactivated by promoter methylation. We have previously shown that loss of SFRP1 protein expression is a common event in breast tumours that is associated with poor overall survival in patients with early breast cancer. To investigate the cause of SFRP1 loss in breast cancer, we performed mutation, methylation and expression analysis in human primary breast tumours and breast cell lines. No SFRP1 gene mutations were detected. However, promoter methylation of SFRP1 was frequently observed in both primary breast cancer (61%, n=130) and cell lines analysed by methylation-specific polymerase chain reaction (MSP). We found a tight correlation (P<0.001) between methylation and loss of SFRP1 expression in primary breast cancer tissue. SFRP1 expression was restored after treatment of tumour cell lines with the demethylating agent 5-aza-2'-deoxycytidine. Most interestingly, SFRP1 promoter methylation was an independent factor for adverse patient survival in Kaplan-Meier analysis. Our results indicate that promoter hypermethylation is the predominant mechanism of SFRP1 gene silencing in human breast cancer and that SFRP1 gene inactivation in breast cancer is associated with unfavourable prognosis.

GABAB heterodimeric receptors promote Ca2+ influx via store-operated channels in rat cortical neurons and transfected Chinese hamster ovary cells

The GABAB receptors are generally considered to be classical Gi-coupled receptors that lack the ability to mobilize intracellular Ca2+ without the aid of promiscuous G proteins. Here, we report the ability of GABAB receptors to promote calcium influx into primary cultures of rat cortical neurons and transfected Chinese hamster ovary cells. Chinese hamster ovary cells were transfected with GABAB1(a) or GABAB1(b) subunits along with GABAB2 subunits. In experiments using the fluorometric imaging plate reader platform, GABA and selective agonists promoted increases in intracellular Ca2+ levels in transfected Chinese hamster ovary cells and cortical neurons with the expected order of potency. These effects were fully antagonized by selective GABAB receptor antagonists. To investigate the intracellular pathways responsible for mediating these effects we employed several pharmacological inhibitors. Pertussis toxin abolished GABAB mediated Ca2+ increases, as did the phospholipase Cbeta inhibitor U73122. Inhibitor 2-aminethoxydiphenyl borane acts as an antagonist at inositol 1,4,5-trisphosphate receptors and at store-operated channels. In all cell types, 2-aminethoxydiphenyl borane prevented Ca2+ mobilization. The selective store-operated channel inhibitor 1-[2-(4-methoxyphenyl)-2-[3-(4-methoxyphenyl)propoxy]ethyl-1H-imidazole hydrochloride prevented increases in intracellular Ca2+ levels as did performing the assays in Ca2+ free buffers. In conclusion, GABAB receptors expressed in Chinese hamster ovary cells and endogenously expressed in rat cortical neurons promote Ca2+ entry into the cell via the activation of store-operated channels, using a mechanism that is dependent on Gi/o heterotrimeric proteins and phospholipase Cbeta. These findings suggest that the neuronal effects mediated by GABAB receptors may, in part, rely on the receptor's ability to promote Ca2+ influx.

[Epigenetic inactivation of the WNT antagonist SFRP1 in breast cancer]

The WNT signalling pathway plays a central role during embryonic development of multi-cellular organisms, especially for the temporal and spatial specification of organs (e.g. WNT4 in kidney development), a process called pattern formation. Interestingly, genes of the WNT pathway are deregulated in a variety of solid tumours, being considerably up- or down-regulated compared to their expression in the corresponding normal tissue. Some members like WNT1 have demonstrated oncogenic properties in animal models. The SFRP1 gene on chromosome 8 p12 is a negative regulator of the WNT pathway. SFRP1 protein is supposed to bind WNT1 molecules thereby inhibiting the activation of frizzled receptors and the WNT pathway. Characterising an SFRP1-specific antibody we could show that loss of SFRP1 is an extremely common event in breast cancer, i.e. SFRP1 was considerably down-regulated in 73% (n = 1967) of analysed invasive breast cancers. SFRP1 loss is associated with unfavourable prognosis in early breast cancer (pT1 tumours). To analyse the cause of SFRP1 inactivation in breast cancer we performed a parallel expression and promoter methylation analysis in human breast cancer and tumour cell lines. RT-PCR techniques and methylation-specific PCR (MSP) were applied. All tumorigenic cell lines analysed exhibited complete promoter methylation and did not express detectable amounts of SFRP1 mRNA. SFRP1 expression could be restored in these cell lines after treatment with 5-Aza-2'-deoxycytidine, a demethylating agent. Human primary breast cancer was methylated in nearly 75% of cases. Our results indicate that epigenetic inactivation by methylation is the predominant mechanism of SFRP1 gene silencing in breast cancer.

The combination of pamidronate and calcitriol reverses particle- and TNF-α-induced altered functions of bone-marrow-derived stromal cells with osteoblastic phenotype

Periprosthetic bone loss after total joint arthroplasty is a major clinical problem resulting in aseptic loosening of the implant. Among many cell types, osteoblasts play a crucial role in the development of peri-implant osteolysis. In this study, we tested the effects of calcitriol (1α,25-dihydroxy-vitamin-D3) and the bisphosphonate pamidronate on titanium-particle- and TNF-α-induced release of interleukin-6 and suppression of osteoblast-specific gene expressions in bone-marrow-derived stromal cells with an osteoblastic phenotype. We monitored the expression of procollagen α1[1], osteocalcin, osteonectin and alkaline phosphatase mRNAs by Northern blots and real-time reverse transcription and polymerase chain reaction analyses. The release of various cytokines was also analysed by ELISA.

We found that calcitriol or pamidronate could only partially recover the altered functions of osteoblasts when added alone. Only a combination of these compounds restored all the tested functions of osteoblasts. The local delivery of these drugs may have therapeutic potential to prevent or to treat periprosthetic osteolysis and aseptic loosening of implants.

Recombinant osteogenic protein-1 upregulates extracellular matrix metabolism by rabbit annulus fibrosus and nucleus pulposus cells cultured in alginate beads

This study was performed to determine if recombinant human osteogenic protein-1 (rhOP-1) is effective in promoting matrix synthesis and matrix formation by rabbit nucleus pulposus (NP) and annulus fibrosus (AF) cells cultured in alginate beads. The effects of culturing the cells in the presence of various concentrations of rhOP-1 were assessed by measuring changes in cell proliferation, proteoglycan (PG) and collagen synthesis and mRNA expression, and in the matrix contents of PG and collagen, as indicators of matrix accumulation. At high concentrations, rhOP-1 had a moderate mitogenic effect on both NP and AF cells. It also stimulated the synthesis of PG and collagen in a dose-dependent manner: this was associated with a corresponding increase in the expression of mRNA for aggrecan core protein and collagen type II. The stimulatory effect of rhOP-1 on PG synthesis was more pronounced than that on collagen synthesis. Continuous treatment with rhOP-1 led to an increase in the total DNA, PG and collagen contents in both NP and AF cultures. The results presented here provide evidence of the ability of rhOP-1 to stimulate the metabolism of both rabbit AF and NP cells cultured in alginate beads.

REM sleep behavior disorder is related to striatal monoaminergic deficit in MSA

OBJECTIVE

To explore the neurochemical basis of REM sleep behavior disorder (RBD) in multiple-system atrophy (MSA).

METHODS

In 13 patients with probable MSA, nocturnal, laboratory-based polysomnography was used to rate the severity of REM atonia loss by the percentage of REM sleep with tonically increased electromyographic (EMG) activity and the percentage of REM sleep with phasic EMG bursts. PET with (+)-[11C]dihydrotetrabenazine ([11C]DTBZ) was employed to measure the density of striatal monoaminergic terminals and SPECT with (-)-5-[123I]iodobenzovesamicol ([123I]IBVM) to measure the density of 123I]IBVM.

RESULTS

Age and gender distributions were similar in patient and normal control groups. The MSA subjects showed decreased mean [11C]DTBZ binding in the striatum (p < 0.0001) and decreased [123I]IBVM binding in the thalamus (p < 0.001). Moreover, in the MSA group, striatal [11C]DTBZ binding was inversely correlated with the severity of REM atonia loss (p = 0.003). Thalamic [123I]IBVM binding, however, was not correlated to the severity of REM atonia loss.

CONCLUSION

Decreased nigrostriatal dopaminergic projections may contribute to RBD in MSA.

Obstructive sleep apnea is related to a thalamic cholinergic deficit in MSA

OBJECTIVE

To explore the neurochemical basis of obstructive sleep apnea (OSA) in multiple-system atrophy (MSA).

METHODS

In 13 patients with probable MSA, nocturnal, laboratory-based polysomnography was used to rate the severity of OSA using the apnea-hypopnea index during sleep. SPECT with (-)-5-[123I]iodobenzovesamicol ([123I]IBVM) was utilized to measure the density of thalamic cholinergic terminals, which project from the brainstem pedunculopontine and laterodorsal tegmental nuclei. PET with (+)-[11C]dihydrotetrabenazine ([11C]DTBZ) was also used to measure the density of striatal monoaminergic terminals, which project from the brainstem. Findings in the patient group were compared with data from 12 normal control subjects scanned utilizing [123I]IBVM and 15 normal control subjects utilizing [11C]DTBZ.

RESULTS

Age and gender distributions were similar in patient and control groups. The MSA subjects showed decreased [123I]IBVM binding in the thalamus (p < 0.001) and decreased mean [11C]DTBZ binding in the striatum (p < 0.0001) in comparison with the control subjects. In the MSA group, thalamic [123I]IBVM binding was inversely correlated with the severity of OSA (p = 0.011). Striatal [11C]DTBZ binding was not correlated with the severity of OSA (p = 0.19).

CONCLUSION

Decreased pontine cholinergic projections may contribute to OSA in MSA.